Diffractive MicroElectroMechanical Systems or MEMs use electrical signals to move micromechanical structures to control or modulate light incident thereon. The incident light beam can be modulated in intensity, phase, polarization or direction. Diffractive MEMS are increasingly being developed for use in spatial light modulators (SLM) used in various applications, including display systems, optical information processing and data storage, printing, and maskless lithography. One shortcoming of existing diffractive MEMS is a low angular light scattering capability, also referred to as scattering angle. Larger angular swings are desirable to enable a larger solid angle of light to be focused onto the SLM without degrading contrast. Angular swing of conventional diffractive MEMS is typically less than about 4° for visible and UV light.
Scattering angle is a strong function of the pitch or spacing between individual diffraction cells of the SLM. As cell pitch is reduced to approximately five times (5×) a wavelength of the modulated light, the scattering angle rapidly increases. However, due to limitations on a minimum feature size that can be fabricated using conventional lithography, the fill factor or reflective efficiency of the SLM also drops below 50% when as cell pitch approaches five times (5×) the minimum feature size.